Pucker of fabrics which are sewn together for example during the formation of a seam, causes considerable production losses in the clothing goods industry. Where a textile is prone to pucker, a "nip and run" sewing technique which requires considerable operator skill, is normally resorted to. However, re-sewing of seams etc is often necessary. Pucker can result from the following causes:
(i) feed pucker caused by the feed mechanism; PA0 (ii) sewing thread tension pucker produced by contraction of the sewing thread; and PA0 (iii) fabric structural jamming pucker caused by fabric structural jamming due to an introduction of sewing thread or needle or both into the fabric during the sewing process.
A number of proposals have been made to reduce seam pucker as caused by the feed mechanism, which can be summarised as follows:
application of rollers to take-up the material during sewing;
application of such feed mechanisms as differential feed, reciprocal feed, compound feed, feeding foot, alternating feed, walking foot, upper and under wheel feed, puller feed;
selecting suitable feed dog teeth. Finer teeth would be more beneficial in reducing pucker;
pressure of presser foot should be kept as low as possible;
the presser foot should just cover the feed area, and be level with it;
direction of sewing should be chosen so as to provide the highest friction between the fabric layers. Generally, sewing in weft direction is recommended;
when sewing different fabrics the fabric with the lower elastic modulus should preferably be the bottom fabric;
application of a sewing aid known as "Krausel Stop" comprising a special self adhesive tape attached to a sewing machine which has a braking effect on the lower fabric;
use of the "nip and run" technique of sewing. This technique involves the operator nipping the fabrics in front and behind the presser foot and then allowing the firmly gripped seam to move forward in synchronisation with the feeding action of the machine. The seam must not be pulled through the machine or retarded in any way.
None of the above proposals are entirely satisfactory.